diff --git a/custom_components/mysmartbike_ble/const.py b/custom_components/mysmartbike_ble/const.py
index e2fa638..24348fa 100644
--- a/custom_components/mysmartbike_ble/const.py
+++ b/custom_components/mysmartbike_ble/const.py
@@ -58,3 +58,9 @@ VOLATILE_FIELDS: Final[dict[str, tuple[str, ...]]] = {
 # it drops; anything shorter is left to the regular poll so a bike that cannot
 # hold a connection does not spin in a reconnect loop.
 MIN_LINK_SECONDS_FOR_FAST_RECONNECT: Final = 5.0
+
+# Granularity of the "Last Seen" entity. Notifications arrive about once a
+# second; publishing each one made this timestamp the single biggest recorder
+# writer in a real installation. Its job - telling you how fresh the values are
+# - needs nothing near that resolution. The precise value is still persisted.
+LAST_SEEN_RESOLUTION: Final = 30  # seconds
diff --git a/custom_components/mysmartbike_ble/coordinator.py b/custom_components/mysmartbike_ble/coordinator.py
index 6b0d0e7..84ca401 100644
--- a/custom_components/mysmartbike_ble/coordinator.py
+++ b/custom_components/mysmartbike_ble/coordinator.py
@@ -35,6 +35,7 @@ from .const import (
     PROTOCOL_REQUEST_MESSAGE,
     CLOSE_MESSAGE,
     SCAN_INTERVAL,
+    LAST_SEEN_RESOLUTION,
     MIN_LINK_SECONDS_FOR_FAST_RECONNECT,
     STORAGE_SAVE_DELAY,
     STORAGE_VERSION,
@@ -172,6 +173,24 @@ class MySmartBikeCoordinator(DataUpdateCoordinator[dict[str, Any]]):
             "disabled" if self._manual_disconnect else "enabled",
         )
 
+    @callback
+    def _publish_last_seen(self) -> None:
+        """Move the entity-visible timestamp forward at most every 30 seconds.
+
+        `self._last_seen` stays exact - it is what gets persisted - but writing
+        it to the entity on every notification produced roughly 2800 database
+        rows per hour per bike, more than any other entity in a real install.
+        """
+        if self._last_seen is None:
+            return
+        published = self._parser.state.get("last_seen")
+        if (
+            published is not None
+            and (self._last_seen - published).total_seconds() < LAST_SEEN_RESOLUTION
+        ):
+            return
+        self._parser.state["last_seen"] = self._last_seen
+
     def _persist_data(self) -> dict[str, Any]:
         """Build the payload written to .storage."""
         return {
@@ -427,7 +446,7 @@ class MySmartBikeCoordinator(DataUpdateCoordinator[dict[str, Any]]):
         except Exception:
             state["rssi"] = None
 
-        state["last_seen"] = self._last_seen
+        self._publish_last_seen()
         _LOGGER.debug(
             "%s: connected=%s advertisements_seen=%s rssi=%s",
             self._address,
@@ -509,7 +528,7 @@ class MySmartBikeCoordinator(DataUpdateCoordinator[dict[str, Any]]):
         self._parser.handle_message(bytes(data))
 
         self._last_seen = dt_util.utcnow()
-        self._parser.state["last_seen"] = self._last_seen
+        self._publish_last_seen()
         self._schedule_save()
 
         # Update coordinator data
diff --git a/custom_components/mysmartbike_ble/sensor.py b/custom_components/mysmartbike_ble/sensor.py
index 076f2d9..62b1b38 100644
--- a/custom_components/mysmartbike_ble/sensor.py
+++ b/custom_components/mysmartbike_ble/sensor.py
@@ -28,6 +28,17 @@ from .const import DOMAIN, MANUFACTURER, MODEL, CONF_DEVICE_NAME
 from .coordinator import MySmartBikeCoordinator
 
 
+def round_km(value: Any) -> float | None:
+    """Round a distance to 0.1 km.
+
+    The ebikemotion frames carry these as `read32 / 10000`, which yields four
+    decimals of false precision - 14.6065, 14.6529, 14.6297 for a range that is
+    really "14.6". Every flicker in the last digit would be another state write
+    and another database row.
+    """
+    return None if value is None else round(float(value), 1)
+
+
 def safe_get(data: dict[str, Any] | None, *keys: str) -> Any:
     """Safely get nested dictionary values."""
     if data is None:
@@ -108,7 +119,7 @@ SENSORS: tuple[MySmartBikeSensorEntityDescription, ...] = (
         device_class=SensorDeviceClass.DISTANCE,
         state_class=SensorStateClass.TOTAL_INCREASING,
         icon="mdi:counter",
-        value_fn=lambda data: safe_get(data, "ebm", "odometry"),
+        value_fn=lambda data: round_km(safe_get(data, "ebm", "odometry")),
     ),
     MySmartBikeSensorEntityDescription(
         key="range",
@@ -117,7 +128,7 @@ SENSORS: tuple[MySmartBikeSensorEntityDescription, ...] = (
         device_class=SensorDeviceClass.DISTANCE,
         state_class=SensorStateClass.MEASUREMENT,
         icon="mdi:map-marker-distance",
-        value_fn=lambda data: safe_get(data, "ebm", "autonomy"),
+        value_fn=lambda data: round_km(safe_get(data, "ebm", "autonomy")),
     ),
     MySmartBikeSensorEntityDescription(
         key="trip_distance",
@@ -126,7 +137,7 @@ SENSORS: tuple[MySmartBikeSensorEntityDescription, ...] = (
         device_class=SensorDeviceClass.DISTANCE,
         state_class=SensorStateClass.TOTAL_INCREASING,
         icon="mdi:bike",
-        value_fn=lambda data: safe_get(data, "ebm", "trip_odometry"),
+        value_fn=lambda data: round_km(safe_get(data, "ebm", "trip_odometry")),
     ),
     MySmartBikeSensorEntityDescription(
         key="trip_range",
@@ -136,7 +147,7 @@ SENSORS: tuple[MySmartBikeSensorEntityDescription, ...] = (
         state_class=SensorStateClass.MEASUREMENT,
         icon="mdi:map-marker-distance",
         entity_registry_enabled_default=False,
-        value_fn=lambda data: safe_get(data, "ebm", "trip_autonomy"),
+        value_fn=lambda data: round_km(safe_get(data, "ebm", "trip_autonomy")),
     ),
     MySmartBikeSensorEntityDescription(
         key="light",
diff --git a/tests/components/mysmartbike_ble/test_restore.py b/tests/components/mysmartbike_ble/test_restore.py
index 106ae50..60a09ac 100644
--- a/tests/components/mysmartbike_ble/test_restore.py
+++ b/tests/components/mysmartbike_ble/test_restore.py
@@ -537,3 +537,68 @@ async def test_no_fast_reconnect_when_link_died_immediately(
         coordinator._async_client_disconnected(coordinator._client)
         await hass.async_block_till_done()
         mock_connect.assert_not_called()
+
+
+async def test_last_seen_is_throttled(
+    hass: HomeAssistant,
+    restore_config_entry: MockConfigEntry,
+    mock_bleak_client,
+    mock_device_in_range,
+    freezer,
+) -> None:
+    """A timestamp that moves on every packet floods the recorder.
+
+    Notifications arrive about once a second; the entity only needs to say how
+    fresh the values are, so it moves at LAST_SEEN_RESOLUTION granularity while
+    the exact time is still what gets persisted.
+    """
+    from custom_components.mysmartbike_ble.const import LAST_SEEN_RESOLUTION
+
+    await setup_offline(hass, restore_config_entry)
+    coordinator = restore_config_entry.runtime_data
+    frame = bytearray.fromhex("246a245a2300008402e1000001f50148494a2340")
+
+    coordinator._notification_handler(0, frame)
+    first = coordinator.data["last_seen"]
+    assert first is not None
+
+    # A burst of notifications inside the window must not move the entity
+    for _ in range(10):
+        freezer.tick(timedelta(seconds=1))
+        coordinator._notification_handler(0, frame)
+    assert coordinator.data["last_seen"] == first
+    # ...while the persisted timestamp keeps tracking reality
+    assert coordinator.last_seen > first
+
+    # Past the window it moves again
+    freezer.tick(timedelta(seconds=LAST_SEEN_RESOLUTION))
+    coordinator._notification_handler(0, frame)
+    assert coordinator.data["last_seen"] > first
+
+
+async def test_distances_are_rounded_to_100m(
+    hass: HomeAssistant,
+    hass_storage,
+    restore_config_entry: MockConfigEntry,
+    mock_bleak_client,
+    mock_device_out_of_range,
+) -> None:
+    """Four decimals of false precision would be a database row each."""
+    seed_storage(
+        hass_storage,
+        {
+            **STORED_STATE,
+            "ebm": {
+                **STORED_STATE["ebm"],
+                "odometry": 806.1488,
+                "autonomy": 14.6065,
+                "trip_odometry": 12.3456,
+                "trip_autonomy": 58.9876,
+            },
+        },
+    )
+    await setup_offline(hass, restore_config_entry)
+
+    assert hass.states.get(entity_id_for(hass, "_odometer")).state == "806.1"
+    assert hass.states.get(entity_id_for(hass, "_range")).state == "14.6"
+    assert hass.states.get(entity_id_for(hass, "_trip_distance")).state == "12.3"